Process for converting petroleum hydrocarbons



Aug. 21, 1934. H. E. wlDDELL PROCESS FOR CONVERTING PETROLEUMHYDROCARBONS Filed May 2l, 1924 mvv www.'

INVENTOR.

ATTv RNEY.

Patented Aug. 21, 1934 PROCESS FOR CONVERTING PETROLEUM HYDROCARBONSHenry E. Widdell, Kansas City, Mo., assignor, by mesne assignments, toGasoline Products Company, Inc., Wilmington, Del., a corporation ofDelaware Application May 21, 1924, Serial No. 714,845

Claims. (Cl. 196-51) This invention relates to improvements in a processfor converting. petroleum hydrocarbons, and refers more particularly toa process in which relatively heavy oils are converted to oils of a 5lighter character having substantially the qualities of commercialgasoline.

Among the objects of the invention are, to provide a process combining certain advantages among which are the utilization of the charging stockas a refluxing medium circulated through a closed coil in adephlegmating tower without being brought into intimate contact with thelight vapors passing therethrough; to provide a process in which thecharging stock, after being preheated and converted in a reacting stageis directed and circulated through a body of reux condensate collectedin the bottom of the dephlegmating tower whereby a portion of the heatcontained in the converted oil is transmitted to the condensate, drivingoff additional vapors therefrom and simultaneously therewith thesynthetic crude or converted product is relieved of excess heat whichpermits of the more accurate control in the subsequent vaporizing stage;to provide a process in which two charging stocks of a relativelydifferent nature are simultaneously treated in separate portions of aunit and blended in an evaporator, producing an improved distillate oncondensation and a better quality bottom; to provide a process whichpreferably is operated continuously and one in which alarge amount ofoil may be treated over a relatively short period of time, and ingeneral, to provide an apparatus for carrying out this process.

The single figure is a diagrammatic view showing the separate units andtheir connections. The placing of the different stages has been variedin order to produce a more compact ligure.

Referring to the drawing, at 1 is shown a furnace in which is mounted anupper bank of coils 2 and a lower bank of coils 3 connected by atransfer line 4. 5 is a reaction chamber preferably made of a steelforging and adapted to withstand high pressures ranging up to 1,000 to1,500 pounds per square inch. At 6 is shown an evaporator connected by avapor line 'I to the condensing tower 8 which in turn is connected by apipe 9 to the refluxing or dephlegmating tower 10 whose interior ispreferably of a bubble tower construction. At ll is shown a gasoline At16 is shown a separate furnace in which is mounted a continuous coil orpipevstill 1'7. Both of the furnaces 1 and 16 are preferably heated bymeans of gas burners not shown.

Describing now more in detail the manner in which the oil is circulatedthrough the system, charging stock from any convenient sourd`- prferably having the characteristics of lacroseiiie, gas oil or the like isintroduced through the line 17. This charging stock is forced by meansci high pressure pump 18 either directly through the by-pass line 19'controlled by a valve 20 ro the upper coil 2 mounted in the furnace lor may be charged through the line 21 controlled n by a valve 22 andcirculated through a preheating coil 23 positioned in the upper portionof the relluxing tower 10. This relatively cool oil, while beingpreheated by the hot vapors rising through the tower, also serves as arefluxing agent condensing out the relatively higher boiling pointfractions from the vapors and knocking them back into the tower throughwhich they gravitate against the flow of the vaporous hydrocar bonfractions. This preheated charging stock is returned through the line23' and is introduced into the upper bank of tubes 2 in the furnace 1where it is further heated and passed, through the transfer line 4 intothe lower baril: of l tubes 3 while therein being rapidly brought to aconversion temperature. While in a condi tion of incipient conversion,that is, while the oil is at a cracking temperature but before anysubstantial decomposition has taken place, the highly heated stock isdirected through the transfer line 24 to the reaction chamber 5 in whichit is collected in a substantial body" moving slowly to the outlet endand to the discharge line 25,

4This reaction chamber permits not only the collection of the oil in asubstantial body where digestion may take place, but introduces a timeelement in the oils conversion. It is in this reaction chamber that thecracking reaction is consummated. The temperature and pressureconditions are controlled in order to prevent any substantialvaporization, that is, the conversion or cracking conditions are soregulated that the conversion takes place substantially in the liquidphase. This digestion, or rearrangement of the molecular bodies in theoil, results in what is termed as a synthetic crude which is drawn offthrough the valve 26 and discharge line 25. This synthetic crude is of arelatively different nature than the charging stock in that the oil bodynow contains a relatively larger percent of lighter or lower boilerpoint fractions which may be readily driven off by subsequentdistillation.

In order to utilize the contained heat in the oil to distill off theselighter fractions, thereby reducing materially the heat loss in thesystem, the oil is directed through the line 25 either directly througha .by-pass 27 controlled by a valve 28 and through the line 29 to theevaporator 6 or, under certain conditions, it is circulated through theline 30 and coil 31 positioned in the tower 10, thence through the line32 back into the line 29 to the evaporator i5. This latter coursethrough the coil 31 is adopted when the cil contains excessive heat,that is, under conditions where there would be an excessive vaporizationif the oil were introduced directly to the evaporating tower. Suchconditions arise when a relatively light oil is treated, such askerosene oil. With certain of the heavier oils, such as heavy gas oil,the temperature as it is withdrawn from the reaction chamber is notexcessive and does not produce excessive vaporization in the evaporator.This difference is primarily due to the heat necessary to distill ofthelighter oils of different characters. vIf circulated through the coil 31in the tower 10, the oil is surrounded by a cooler medium or refluxcondensate which has been separated out in the tower and to which heatis transmitted, serving to reboil this reflux condensate and drive offadditional vaporcus fractions while the synthetic crude circulatedthrough the coil is relieved of its excessive temperature and reduced toa condition where more suited to proper vaporizing conditions whenreleased in the evaporator 6. The function of the valve 26 is to relievethe pressure on the synthetic crude v'hich results in the drawing off ofthe lighter fractions in the evaporator tower 6.

Simultaneously with this treatment in the cracking portion of theapparatus, there is introduced through the line 33 a charging stock ofrelatively heavier oil, preferably an oil having the characteristics ofcommercial fuel oil,-a product from which the lighter fractionsincluding benzine, kerosene and gas, oil cuts have been removed. Thischarging stock is charged by means of the pump 34 either directlythrough the by-pass line 35 to the line 36 communicating with the pipestill 171, or it may be circulated through the line 37 in which isinterposed the heating coils 38 positioned in the condenser tower 8. Ifcirculated through the pipe 37, after preheating, it is returned anddirected through the line 36 to the pipe still 171 where it is heated toa temperature sufficient to vaporize off a substantial portion of theoil bodies contained therein. The fluid oil products from the pipe stillpass through the line 39 and are introduced in an evaporatorvsimultaneously with the syntheticl crude from the cracking unit.

This blending of the highly heated oils in the evaporator' serves notonly to promote the evolution of vapors but also has the advantage ofproducing a blended bottom which is drawn off through the pipe 40 inwhich is interposed a valve 4l controlled by an automatic liquid levelregulating device 42. Normally, when the lighter fractions are distilledfrom the synthetic crude with the contained heat in the oil and a largepercentage of the oil passed overhead as vapor, the resulting bottom isobjectionable due to the presence of considerable quantities of freecarbon which makes the product objectionable when utilized as fuel oil.Likewise, when fuel oil is treated in a pipe still, and considerablequantities of the oil driven overhead, the resulting residual materialis of a relatively viscous nature and only uid at high temperature. Whenthe products are combined or blended in the manner described thereresults a bottom which is a free flowing oil with a relatively highdegree of fluidity at 32 F. or 0" C. This bottom can be readilycirculated through pipe lines even at low temperatures. Free carbon iscontained in this bottom to an amount not materially in excess of threepounds per barrel, and when operating on some types of oil the carboncont-ent runs materially below one pound per barrel. In some cases, itis scarcely discernible. The residual material or bottom which collectsin the evaporator as described is drawn off through the line 40, passedthrough a cooling coil 43 and is directed through the line 44 to a fueloil storage.

The overhead material distilled off from the oil body rises and passesthrough the packing material diagrainmatically shown at 45. These vaporsare directed through a line 7 to a condenser tower wherein partialcondensation is effected due to loss of heat through radiation and thecirculation of the cool fuel oil charging stock through coils 38positioned in the tower.

The reiiux condensate separated out in the tower 8 is automaticallywithdrawn through the line 45 controlled by the liquid level regulatingdevice diagrammatically shown at 46, This reflux material passes fromthe line 45 through the line 46 to a recharging stock cooler 47, thenceto a recharging stock storage through the line 48.

The overhead material from the partial condenser tower 8 is directedthrough the line 49 to the refluxing or dephlegmating tower 10 which ispreferably of bubble type construction. The vapors rising through thistower are subjected therein to the refluxing action of a plurality ofpools of relatively cooler oil which serve to separate out the higherboiling point fractions and gravitate these fractions downwardly to apool maintained in the bottom of the tower by means of a liquid levelregulating device 50. This condensate maintained inthe bottom of thetower is subjected to the reheating action of the synthetic crude whenthe same is circulated through the coil 31. It is drawn off aftercollection by the liquid level regulating device through the dischargeline 51 in which is interposed a valve 52 and is directed with thecondensate from the partial condensing tower 8 through the line 46 andrecharging stock cooler 47 The final vapors or gasoline fractions passover from the top of the tower through the line 12 to the gasolinecondenser 1l from which the distillate is discharged through the coolingcoil 13 and through the line 14 to the gas separator 15. Theincondensible gas is withdrawn through the pipe 53 controlled by a valve54, while the liquid drawoif through the line 55 is similarly controlledby a liquid level regulating device 56.

The process permits of continuously treating oils of a relativelydifferent character and uti lizes as recharging stock the bottomsrecovered from the separate stages whereby a more-com plete treatment iseffected and the heat loss materially reduced. Furthermore, whereverpossible it will be noted that the contained heat of the oil is utilizedto preheat incoming cooler oil or the cooler oil utilized to reux orseparate out objectionable higher boiling point fractions. The

such as fuel oil, in combination with a cracking system whileeliminating the objectionable features of cracking fuel oil direct.

It is appreciated that the different stages may be redesigned andchanged as to construction and connections altered without departingfrom the spirit of the invention. Broadly, the invention covers thesimultaneous treatment of oils of a relatively different character toproduce an increased and improved quality distillate and at the sametime improving the character of the residual material or bottoms may beconsidered by-products of the process.

I claim as my invention:

1. A process of converting oil comprising separately and simultaneouslytreating charging stocks of a relatively different character, one in acoil and enlarged chamber under such conditions of temperature andpressure as to crack the oil while maintaining it in substantiallyliquid phase, the other in a tube still wherein it is treated undertemperatures sufficient to distill off a major portion thereof,combining the heated oils in a separate evaporating stage maintained atreduced pressure to vaporize the lighter fractions of the combined oils,dephlegmating the vapors in separate successive stages, passing onecharging stock through one of the dephlegmating stages, passing theother charging stock through the other dephlegmating stage before theiradmission to the heating stages, recycling unvaporized residues from theevaporating stage and reux condensate from the dephlegmating stages tothe heating stages for retreatment.

2. A process of converting hydrocarbons comprising heating an oil toconversion temperatures and under a high pressure, passing the heatedoil before any substantial decomposition takes place, to a reactionstage wherein the oil is maintained for a time sufcient for conversionto take place, controlling the temperature and pressure on said oil toprevent any substantial distillation of the oil, heating a chargingstock of relatively different character in a heat distillation stage toa temperature sufficient to distill off a portion thereof, combining theoils in an evaporating stage maintained at a pressure materially belowthat in the conversion stage whereby the lighter fractions of thecombined oils are evaporated, and to produce a fuel oii residue having ahigh degree of fluidity at low temperatures and a low content of freecarbon, dephlegmating the vapors in a series of stages, condensing thedephlegmated vapors and recycling fuel oil residue from the evaporatingstage to the heat distillation stage, and passing. each of the chargingstocks through different ones of the said dephlegmating stages topreheat each stock before its admission to the heating stage to which itis charged.

3. A process of converting hydrocarbons comprising heating an oil toconversion temperatures and under a high pressure, passing the heatedoil before any substantial decomposition takes place to a reaction stagewherein the oil is maintained for a time sufficient for conversion totake place, controlling the temperature and pressure on said oil toprevent any substantial distillation of the oil, heating a chargingstock of relatively different character in a heat distillation stage toa temperature sufficient to distill off a major portion thereof,combining the oils in an evaporating stage maintained at a reducedpressure to vaporize the lighter fractions of the oils and to produce afuel oil residue having a high fluidity at low temperatures and a lowcontent of free carbon, dephlegmating the vapors in a series of stages,preheating the stock charged to the heat distillation stage by passingit in heat exchange relation with the vapors in one of the dephlegmatingstages, and recycling a portion of the fuel oil residue to said heatdistillation stage.

4. The method of continuously skimming and cracking hydrocarbons whichcomprises skimming but not substantially cracking a stream of crude oilby heating the stream under pressure to a temperature high enough tovaporize gas oil and lighter fractions, transmitting the resultantmixture to an expansion chamber, depositing the carbonaceous residualoil in said chamber and maintaining the pressure therein low enough torelease said gas oil and lighter fractions in the form of vapors,removing said residual oil from the system, subjecting said vapors toreflux condensation under a pressure lower than the rst mentionedpressure and thereby condensing the gas oil fraction of the crude oil,cracking the condensed gas oil by pumping it through a cracking coilunder a higher pressure, transmitting the cracked mixture from said coilto a chamber and separating the vapors from the carbonaceous residuumtherein, removing said residuum from the system, subjecting the crackedvapors to reflux condensation, and mixing the resultant refluxcondensate with said gas oil fraction of the crude oil passing to saidcracking coil, so as to subject the mixture to the cracking operation,and transmitting heat from said cracked vapors to said stream of crudeoil before said stream is heated to vaporize the gas oil.

5. The method of continuously skimming and cracking hydrocarbons whichcomprises skimming but notl substantially cracking a stream of crude oilby heating the stream" under pressure to a temperature high enough tovaporize the gas oil and lighter fractions, transferring the resultantmixture to an expansion chamber, depositing the carbonaceousresidual oilin said chamber and maintaining the pressure therein low enough torelease said gas oil and lighter fractions in the form of vapors,removing said residual oil from the system, subjecting said vapors toreflux condensation under a pressure lower than the first mentionedpressure and thereby condensing the gas oil fraction of the crude oil,cracking the con densed gas oil by forcing it through a cracking coilunder a higher pressure, passing the cracked mixture from said coil to avaporizing chamber and separating the vapors from the carbonaceousresiduum therein, removing said residuumfrom the system, subjecting thecracked vapors to re-y flux condensation, mixing the resultant refluxcondensate with said gas oil fraction of the crude oil passing to saidcracking coil so as to subject the mixture to the cracking operation,and subjecting the stream of crude oil to heat exchange with the blendedvapors of both the skimming and cracking operations before said streamis discharged into said expansion chamber.

HENRY E. WIDDELL.

